It has previously been established by this Laboratory that the formation of p-bromophenol from bromobenzene occurs via bromobenzene 3,4-oxide, but o-bromophenol could arise either via the 2,3-epoxide or the 1,2-epoxide, or by direct insertion of oxygen. Using 2,4,6-trideuterobromobenzene we have shown that o-bromophenol arises predominantly from the 2,3-epoxide intermediate although the addition of oxygen to the 2-position carbons, followed by an NIH shift and rearrangement, cannot be ruled out.